There are a number of implantable medical devices, such as indwelling catheters, that are used for the repeated and prolonged access to a patient's vascular system, urinary system, or other bodily conduits. Such devices include peripherally-inserted central catheters (“PICC's”), central venous catheters (“CVC's”), dialysis catheters, implantable ports, midline infusion catheters, and drainage catheters. These devices are typically implanted into a patient for an extended period of time to allow for multiple treatments, such as the delivery of therapeutic agents or dialysis treatments. Use of such devices eliminates the need for multiple placements of single-use devices, thus reducing the risk of infection and placement complications, and reducing the overall cost of patient care. Examples of such implantable medical devices include Vaxcel® PICC's and ports, Xcela® PICC's and ports, Vaxcel® Plus Chronic Dialysis catheters, and the Exodus™ drainage catheter (all from Navilyst Medical, Inc., Marlborough, Mass.).
Like any implantable device placed into the bloodstream, PICC's, ports, and other similar indwelling devices are susceptible to occlusion due to factors relating to thrombosis, encrustation, and the like. Catheter occlusion remains one of the most common noninfectious complications of long-term indwelling devices. Such occlusions can result in catheter malfunction, infection, and/or major vessel thrombosis. Thrombotic causes for catheter obstruction include intraluminal thrombus, extraluminal fibrin sleeve, mural thrombus, or major vessel occlusion and present as either complete or partial occlusion. For example, venous catheters may become encased with a fibrin material shortly after placement within a patient. This fibrin sheath is believed to be comprised of fibrin, platelets, and/or a fibrous collagen substance, and can lead to subsequent catheter occlusion.
In other types of indwelling catheters, such as those that are inserted into the urinary system, catheter occlusion may result from infection of the urine by a urease producing bacteria. Such infection may lead to the formation of a thickening biofilm that results in catheter occlusion. Occlusion may also result from the crystallization of salts from bodily fluids onto the catheter. It is estimated that recurrent blockage of urinary catheters occurs in as many as 50% of long-term catheterized patients.
Current techniques used to minimize, prevent, or treat catheter occlusion include flushing the catheter with fluids, such as heparinized saline to prevent thrombus formation, or citric acid to dissolve encrustation. It would be advantageous, however, to provide catheters that include means to minimize, prevent, disrupt, and/or treat occlusion.